Objective: To explore the early diagnostic value of thrombus molecular markers in thrombosis ofpatients with malignant tumors and to evaluate their risk factors. Methods: Diagnostic research.A total of 1366 patients (including lung cancer, breast cancer and colorectal cancer,) were randomly selected in the Red Flag Hospital of Mudanjiang Medical College and Mudanjiang Cancer Hospitalfrom September 2009 to February 1919. Among them, 562 were males and 804 were females with average age (59.45±15.10) years old. The control group consisted of 70healthy donors (35 males and 35 females, with an average age of (49.60±19.12) years old), including 69 cases of venous thrombosis (thrombotic group, 32 males and37 females, with an average age of (61.20±15.71) years old).Chemoluminescent enzyme immunoassay was used to detect thromboregulatory proteins(TM), thrombin-antithrombin complexes(TAT), tissue plasminogen activators/inhibitors -1 complexes(t-PAIC), plasminase-anti-fibrinolysis complexes(PIC) in venous plasma. According to the sensitivity and specificity of each marker, the receiver′s work characteristic curve was drawn to evaluate its diagnostic performance. Cox regression analysis was used for single-factor and multi-factor risk analysis. Results: The incidence of venous thromboembolism(VTE) in patients with different types of malignant tumors was statistically significant, with lung cancer being the highest, followed by colorectal cancer and breast cancer(P<0.05). The levels of TM, TAT, t-PAIC and PIC were significantly higher in the lung, breast and colorectal thrombosis group than in the control group. The differences were statistically significant(all P<0.05). The optimal cut-off level for TM is 10.57 IU/ml(sensitivity 50.30%, specificity 75.50%, AUC=0.671), and the optimal cut-off level for TAT is 4.16 ng/ml(sensitivity is 80.30%, specificity is 62.80%, AUC=0.757).The optimal truncation level for t-PAIC is 11.44 ng/ml(sensitivity 52.50%, specificity 84.00%, AUC=0.682), and the optimal truncation level for PIC is 1.18μg/ml(sensitivity 67.20%, specificity is 79.50%, AUC=0.790). The combined detection of the four molecular markers has the best sensitivity and diagnostic performance(86.90%, AUC=0.807). Age, stage, metastasis, surgery, tumor diameter, and PIC levels are independent factors that affect the occurrence of VTE in malignant tumors (all P<0.05). Conclusions Different types of malignant tumors have different rates of thrombosis. The combined detection ofTM, TAT, t-PAIC and PIC have the best diagnostic performance, and can be used as a new early diagnosis method for VTE in malignant tumors. Age, stage, metastasis, surgery, and tumor diameter are risk factors for VTE in malignant tumors. PIC levels can be used as a reliable markerfor the risk of VTE in patients with malignant tumors within 6 months.